This invention relates generally to medication infusion pumps, particularly of the type adapted for implantation directly into the body of a patient and for programmed operation to deliver a selected medication through a catheter to the patient over an extended period of time. More specifically, this invention relates to an improved implantable infusion pump having a discharge side access port which can be used to clean or flush residue from the pump and/or within the catheter.
Medication infusion pumps are generally known in the art for use in delivering a selected medication to a patient in a scheduled or preprogrammed manner. In recent years, infusion pumps have been developed in compact form and adapted for direct implantation into the body of a patient, to deliver a specific medication such as insulin to the patient in discrete doses over an extended period of time. An implantable infusion pump of this general type includes an internal medication chamber or reservoir for receiving and storing a supply of the selected medication in liquid form, in combination with a miniature pump mechanism and associated programmable control means for operating the pump mechanism to deliver discrete doses of the medication from the internal storage reservoir and through a catheter to the patient. A refill port is provided on the pump to permit transcutaneous needle access for purposes of periodically refilling the pump reservoir with a fresh supply of medication. For one illustrative example of an implantable medication infusion pump of this general type, see U.S. Pat. No. 4,573,994.
Implantable and programmable medication infusion pumps offer significant potential advantages to patients who are required to comply with a long term medication treatment regimen. Such implantable pumps can operate automatically, with little or no patient intervention, to administer an important medication such as insulin to a diabetic patient on a regular basis.
However, it is known that particle-like residues can accumulate over a period of time within the pump mechanism and the related discharge catheter of an implantable infusion pump. Such residues are believed to be the result of shear denaturation and/or precipitation of pharmaceutical components, especially in the case of relatively complex molecule and/or protein-based medications such as insulin and the like. These particle-like residues can collect in sufficient quantity to reduce the medication stroke volume of the pump mechanism and, in some cases, to occlude the discharge catheter.
Various techniques have been proposed to flush accumulated residues from the flow passages associated with an implantable medication infusion pump. For example, it is known to inject a suitable cleaning agent into the pump reservoir, and then operate the pump in a manner to circulate the cleaning agent through pump flow passages and through the discharge catheter in an effort to dissolve and/or dislodge accumulated residues. This technique, however, undesirably results in ultimate delivery of the cleaning agent to the patient.
There exists, therefore, a significant need for further improvements in implantable medication infusion pumps, particularly with respect to devices and methods for permitting accumulated residues within pump flow passages to be removed, in a manner which does not require delivery of cleaning agents to the patient. The present invention fulfills these needs and provides further related advantages.